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USOO7915570B2 (12) United States Patent (10) Patent N0.: Cetrulo et a]. (45) Date of Patent: (54) SMART CAMERA WITH AN INTEGRATED 2 , LIGHTING CONTROLLER _ (75) Inventors: Raffaele A. Cetrulo, Aust1n, TX (US); William M. Allai, Austin, TX (U S); - ' . Assignee: National Instruments Corporation, A t- TX (Us) Notlce: _ _ 2/2003 8/2003 Ulrich et 31‘ 9/2005 Fielden et al. _ Paulsen et a1. Ulrich et a1. 2/2007 Roberge et a1. 7,259,522 B2 8/2007 Toyota et al. 7,331,681 B2 7,397,550 B2 2/2008 POhleIT et 31~ 7/2008 Hackney et al. 2005/0236998 Subject to any d1scla1mer, the term of th1s patent is extended or adjusted under 35 A1 7/2004 10/2005 2006/0032921 A1 Thibaud et al. ............. .. 250/205 Mueller et al. 2/2006 Gerst, 111 @131, OTHER PUBLICATIONS “Legend 540”; DVT Machine Vision; 2004; 2 Pages. “PresencePLUS Vision Sensors”; Second Edition; Banner Engineer Appl. N0.: 12/184,931 (22) Filed; 10/2005 1 10 eta . 6,522,777 B1 U.S.C. 154(b) by 368 days. (21) 1cc 6,603,103 B1 6,950,196 B2 2004/0129860 A1 * _ ethql occ 3/2001 Jusoh et al. 7,178,941 B2 us In, (*) I‘ll; , 6,963,175 B2 10/2006 11/2005 Gladnick Archenholdet a1.et a1. 7,127,159 B2 Nlcolas Vazquez, Austln, TX (US) _ Mar. 29, 2011 6,207,946 B1 6,956,963 B2 3n“? 2211110}: Aufin?s T1? FEES),(U S )’_ f‘n“ aw, 011“ _ 0° ’ (73) US 7,915,570 B2 ing Corp.; 2005; 36 Pages. “Cognex Checker”; Cognex Corporation; 2005; 6 Pages. Aug_ 1, 2008 “Cognex DVT LineScan Users Guide”; Cognex Corporation; 20 - (65) - - Pages; Accessed from Internet Jan. 15, 2009; http://www.c0gnexsen Pnor PUbhcatlon Data US 2009/0033761 A1 sors.com/support/DownloadsManager.php?Order:Index& Feb. 5, 2009 KW:DVT%20MaIlua1#~ “Cognex MVS-8000 Series: MVS-8100L Hardware Manual”; Related U_s_ Application Data Cognex Corporation; Oct. 2006; 40 Pages. (60) Provisional application No. 60/953,889, ?led on Aug. 3, 2007. (continued) Primary Examiner * Thanh X Luu (51) Int. Cl. (74) Attorney, Agent, or Firm * Meyertons Hood Kivlin G01J1/32 H053 37/02 (52) (58) (2006,01) (2006.01) Kowert & Goetzel, P.C.; Jeffrey C. Hood us. Cl. ...................................... .. 250/205; 315/308 Field of Classi?cation Search ................ .. 250/205; 315/308 (57) ABSTRACT A smart camera includes an integrated lighting current con troller and can couple to one or more external light sources. See application ?le for complete search history. The integrated lighting current controller can control and power the one or more external light sources using a current (56) References Cited pulse. The one or more external light sources can provide illumination for the smart camera to acquire the image of an US. PATENT DOCUMENTS 5,134,469 A * 5,172,005 A 7/1992 object under test. Uchimura ..................... .. 348/68 25 Claims, 11 Drawing Sheets 12/1992 Cochran et al. Smart Camera 111] FPGA M I— — — — — — — E 750 _ Input 758 User Light . Timing Settings 1 79 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ — — — -|- - — — - I _ _ _ _ _ _ _ _, Lighting Controller LQQ I . = ' m | | I I | | | (752 |WW7I Generation M I 00," am l I l | I 38mm Generation : 1L4 | i 1 | : : Ligsht‘Curr’enl l e pain I I l US$760 I Genera?on Programmed | m Lighlcorrent |__________ _ _'____'l__“_'l'____'l'_“_'l___ 4 sew"? : l— 756 l ' L I : _ 1' Processor Executing er. Algorithm Sequence 12:1 Inspection Pass/Fail Result US 7,915,570 B2 Page 2 OTHER PUBLICATIONS “PD2-1012iPD2 Series Digital Type”; CCS; 2006; Accessed from Internet at http://WWW.ccs-inc.cojp/cgi-bin/hp.cgi?menu:102-201 “Installing the In-Sight 3000”; CogneX Corporation; 2002; 43 Pages. “In-Sight Strobe Light Adapter Installation & Reference”; CogneX Corporation; 2002; 18 Pages. “Tech Note: Connecting a Strobe Device to the In-Sight 1000 and 4000 Series Vision Sensors”; CogneX Corporation; 2003; 12 Pages. “SmaItImage Sensor Installation and User Guide, 7th Edition”; DVT 02-0 1 e. “PS-3012-D24 Strobe Power Supply”; CCS; 2006; Accessed from Internet at http://WWW.ccs-inc.cojp/cgi-bin/hp.cgi?menu:102-201 10-0 1 e. “CogneX Product Guide 2007”; CogneX Corporation; 2007; 10 Pages. Corporation; Aug. 2003; 157 Pages. “FrameWork”; DVT Corporation; 2004; 2 Pages. “Modular Lighting Controller (MLC)”; ETS-Lindgren; 2003; 2 “App 909iPP600 Heat Output”; Gardasoft Vision; 2003; 2 Pages. “PP500 RangeiLED Lighting Controller With Ethernet Interface”; Gardasoft Vision; 2006; 2 Pages. “PP600 Series LED Lighting Controller” Gardasoft Vision; 2003; 2 Pages. Pages. “PP600iLED Lighting Controller for NERLITE MV Lighting “The PP860 Series High Current LED Lighting Controllers”; Gardasoft Vision; 2006; 2 Pages. “Gardasoft Vision User MmualiPPSOO, PP520, PP500F, PP520F LED Lighting Controllers”; Revision 08; Gardasoft Vision; 2007; 28 Components”; Siemens; 2003; 2 Pages. “Installation of TPS-28 Universal Lighting Power Supply”; Execu tive Engineering; May 2004; 25 Pages. “Signatech Intensity Controller Manual MS210 / MS220 / CS410 / CS420”; Advanced Illumination; Feb. 2006; 18 Pages. Pages. “Gardasoft Vision User ManualeP600, PP602, PP610, PP612 LED Lighting Controllers”; Revision 13; Gardasoft Vision; 2006; 32 “Pulsar 710 Controller Operator’s Manual & Installation Guide”; Advanced Illumination; Oct. 2005; 40 Pages. “Signatech Controller Manual S4000 / S6000 / S6000-AS” Advanced Illumination; Oct. 2006; 17 Pages. “GardasoftVision User ManualeP600F, PP602F, PP610F, PP612F LED Lighting Controllers”; Revision 10; Gardasoft Vision; 2003; 32 “Application NoteiPP860 Heat Output”; GardasoftVision; Sep. 29, 2006; l Page. “Application NoteiPP500 Heat Output”; GardasoftVision; 2003; 2 NERLITE MV Lighting Components”; Siemens; 2003; 2 Pages. Pages. Pages. “SCM Strobe Control Module”; Banner Engineering Corp.; May 2001; 4 Pages. Pages. Pages. “PP610iLED Lighting Controller With RS232 Control for “NERLITE SCM-l Strobe Control Module, IVUD”; Siemens; 2003; 2 * cited by examiner US. Patent Mar. 29, 2011 Sheet 1 0f 11 US 7,915,570 B2 Em25u:8tug2s N2£9562 we F 5c:o?8c2i 1/9: 2 F @268% v.QIE:$25$5 US. Patent Mar. 29, 2011 Sheet 2 0f 11 US 7,915,570 B2 1021‘ 1 10 —\ Sma? Camera 192 JEEEEEEEEQEEEQ W @ %W@ , w @ FIG. 2A 110-\ Sma? Camera 192 JEEEEEEEE“®®®®\ @Y @2 @6061@ Y9) Y9 US. Patent Mar. 29, 2011 US 7,915,570 B2 Sheet 4 0f 11 8ESQ O 29$g :GEmeS 1H; $5 $250 3 US. Patent Mar. 29, 2011 Sheet 5 0f 11 US 7,915,570 B2 "FIG.4A IEtxhp/earnOsiton Software 192 I/ODirect Lens 280 SLioguhrtcieng FiCxatmuera Enclosure US. Patent Mar. 29, 2011 Sheet 6 0f 11 FIG. 4C US 7,915,570 B2 US. Patent Mar. 29, 2011 Sheet 7 0f 11 US 7,915,570 B2 2520 .2 m0,me _g_I I_g0520:02_00 O20.6:0 ? n Ig00082_ 2\0WWW [email protected] :82m02 0.03 g__| _ _ _|_E5tFS0E.5I0 0.5|0ch _ I<02?_ nmm0Fn20 025;02 __03.0 25 ,$025me0 4/0: _0I2 02 1 mII4o_Im8502h0m8:é|_gI 1| | _ m _02 90 2 _$005I_ _025m0_2m0 00m_00w_ @_08I02 $d20aQ§5>E0 .GI<6 US. Patent Mar. 29, 2011 US 7,915,570 B2 Sheet 9 0f 11 S3m5u8cg3i$:55BEm=u§<1Mm¢QwS§m58N=%3S$»m?IQ |n _ _ _ _ n _ a _= _ “ _ _2&8 sq: w\la$88:25 _ H _ Q: E _ _ Egon_H_mm“I. at:55 511% »m o?| 1_ :_91\ 3at_ 8 \QQQa "1% 5:3: @250 1_ 1_1 +1 SE:_EgoQQEmw 1" __ $3_wson“ Em: pam4/ 1cg_sn oEn __ Essmm _ " om“H 1\ _§ 1_ “1E_ESQEQ _QRcg_Em:zm_w | coh?mwmw EEG2g g =21 $35 E58_ H1__1 W1Em:El_HI21.-H3l101l 1l1? E$8mgu \ _m_gQEsNSmQwEQE w u_32F1GNE%._9:1sz m$32m=é< 2.? a §5%DEu E?w $925% US. Patent Sheet100f11 B4ar.29,2011 wowk Al 6:20 bmoq Bmco NW \ N EmtMso mum2 US 7,915,570 B2 US 7,915,570 B2 1 2 SMART CAMERA WITH AN INTEGRATED LIGHTING CONTROLLER factors such as ambient light conditions and required expo sure time. Existing lighting current controllers generally use PRIORITY CLAIM Various existing approaches to use light sources with a cam linear power supply designs which are bulky, heavy, and hot. era in machine vision/ image processing applications are described below. Examples of lighting controllers include This application claims priority to provisional patent appli Camera Lighting Circuit with High Power Density and Long BANNER PRESENCE and SCM products, ETS LINDGREN MODULAR LIGHTING CONTROLLER, Strobe Intervals,” to Cetrulo et al., ?led on Aug. 3, 2007. ADVANCED ILLUMINATION SIGNATECH S4000/6000 cation No. 60/ 953 ,889 titled “New Architecture for Industrial and PULSAR products, SIEMENS PP610 product, and GARDASOFT PP420 product, among others. FIELD OF THE INVENTION A ?rst approach may use an external lighting current con troller along with an external power supply. This approach works well but requires additional and external components, The present invention relates to the ?eld of machine vision, and more particularly to a smart camera with an integrated lighting current controller. e. g., an external lighting current controller, and sometimes an additional power supply. Furthermore, if the lighting current DESCRIPTION OF THE RELATED ART In many applications, machine vision or image processing analysis is used to inspect or locate an object. For example, in controller and/ or the power supply use regular linear power, then the power draw and/or heat dissipation may become an issue and may need bigger power supplies and/ or heat dissi 20 manufacturing applications, machine vision analysis may be may be undesirable due to added complexity and cost, as well as additional reliability issues. used to detect defects in a manufactured object by acquiring images of the object and using various types of image pro cessing algorithms to analyze the images. As an example, a system to manufacture electrical components such as capaci Another approach may utilize integrated lights, such as LED’s or other light sources, built into a smart camera. How 25 tors may use machine vision to examine respective sides of ensure that the capacitors are labeled, marked, or color coded 30 the manufacturer, this approach does not solve the user’s application. Furthermore, the built-in lighting solutions mainly use a 35 cameras, line scan cameras, infrared imaging devices, x-ray imaging devices, ultra-sonic imaging devices, and any other type of device which operates to receive, generate, process, or acquire an image or sensor data. Typically, the image processing and analysis of image data ability to directly control and/ or power external light sources. As a result, if the user’s illumination requirements can not be met by the limited selection of integrated lights provided by era or other device may be used to acquire the images to be analyzed in a machine vision application, including digital ever, the integrated lights on a smart camera (e.g., integrated illumination) do not provide the quality and intensity and variety of con?gurations needed for many machine vision applications. Systems with integrated lights do not have the the capacitors in order to detect manufacturing defects, properly, etc. Machine vision applications may use image processing software operable to perform any of various types of image analysis or image processing functions or algorithms in examining an acquired image of an object. Any type of cam pation devices. Some heat dissipation devices, such as fans, 40 is performed by a computing system which may be coupled to the camera. Increasingly, however, such image processing voltage signal to control and power the built-in LED(s). The brightness of an LED is usually controlled by the amount of current through the LED. Using an unregulated or regulated voltage signal that is, by some mechanism, converted to cur rent is not accurate, and precludes the possibility of overdriv ing the LED(s) in a strobing application. SUMMARY OF THE INVENTION capabilities are performed by the camera or sensor by hard Various embodiments of a smart camera system with an ware and/ or software “on-boar ” the device. The term “smart camera” is intended to include any of various types of devices 45 integrated lighting current controller are presented below. In that include a camera or other image sensor and a functional some embodiments, the smart camera may comprise a pro unit (i.e., a processor/memory and/or programmable hard ces sing unit, imager, memory, and an integrated (i.e., built-in) ware, such as a ?eld programmable gate array (FPGA)) lighting current controller. The smart camera may include a capable of being con?gured to perform an image processing housing containing all the elements of the smart camera. The smart camera may also use a built-in imager for image acqui sition, or alternatively it may connect to an external imager/ function to analyze or process an acquired image. Examples of smart cameras include: NAVSYS Corporation’s GI-EYE, 50 which generates digital image data that are automatically tagged with geo-registration meta-data to indicate the precise position and attitude of the camera when the image was taken; Vision Components’ GmbH Smart Machine Vision Cameras, lens/ camera for analog or digital image acquisition. The integrated lighting current controller may be operable 55 which integrate a high-resolution Charge Coupled Device lights. The lighting current controller may be able to strobe the lights substantially aron the time of the exposure, and possibly right before the exposure, such that the unit under test has the desired lighting when the exposure is taken. (CCD) sensor with a fast image-processing signal processor, and provide various interfaces to allow communication with the outside world; and Visual Inspection Systems’ SMART cameras with on-board DSP capabilities, including frame to couple to one or more external light sources, which may be regular of-the-shelf lighting sources such as LED’s or other 60 The lighting current controller uses a switching power grabbers and robot guidance systems, among others. Lighting controllers may be used to power lightheads (light sources) that provide illumination of objects to be imaged. limited power dissipation, it can be integrated into the smart Lighting controllers can use either voltage or current to con the light source by generating a current pulse from the switch trol and power light sources. Lighting current controllers can provide either continuous or strobed current at variable cur rent levels as required for the application, determined by supply that minimizes power dissipation, and because of its camera. The lighting current controller can control and power 65 ing power supply (while in the active state). The switching power supply may receive a pulse-width-modulated (PWM) signal that controls it output, and the PWM signal itself may US 7,915,570 B2 3 4 be controlled by a control loop on the input on the power supply. During intervals when it is desirable not to send any current through the light source, the light source may be contrary, the intention is to cover all modi?cations, equiva lents and alternatives falling within the spirit and scope of the present invention as de?ned by the appended claims. disconnected from the output of the switching power supply. During these intervals the switching power supply cannot DETAILED DESCRIPTION OF THE INVENTION continue to regulate its current output unless a dummy load were connected and thus provide an alternate path for the current output. However, using a dummy load would waste power and increase heat output. Instead, during intervals when the light source is discon Incorporation by Reference The following references are hereby incorporated by ref erence in their entirety as though fully and completely set forth herein: Provisional US. Patent Application No. 60/953,889 titled “New Architecture for Industrial Camera Lighting Circuit nected, the switching power supply may be turned off. Since these intervals are unknown (may be short or long depending on the application) and since during this time the switching power supply is not operating, the values of the components in the control loop may decay with time. Once the control with High Power Density and Long Strobe Intervals,” to Cetrulo et al., ?led on Aug. 3, 2007. US. Pat. No. 7,327,396 titled “Smart Camera with Modu lar Expansion Capability,” to Schultz et al., issued on Feb. 5, loop/switching power supply is inactive, the power supply may take a while to reach the active state again with the desired current accuracy. Thus an active circuit can sample and hold the control values, and thus provide the necessary fast response time to achieve full current accuracy. This can be implemented using 2008. 20 FIG. 1 illustrates an image acquisition system in which a host computer system 102 is coupled to a smart camera 110. As used herein, the term “smart camera” is intended to include any of various types of devices that are operable to a microcontroller having ADC (analog-to-digital converter) and PWM (pulse width modulation) capabilities. With the active circuit, a memory of the control variables can be main tained from when the control loop was regulating the output 25 acquire and/or store an image and which include on-board processing capabilities. A smart camera may thus be further operable to analyze or process the acquired or stored image. Examples of a smart camera include analog and digital cam eras with on-board processors, and other similar types of 30 devices. The smart camera may also include all the elements shown in FIGS. 5-7 without the chassis. Thus the smart cam era may be built into a custom chassis at a later time. As used herein, the term “functional unit” may include a processor and memory or a pro grammable hardware element. current. The active circuit memory enables the lighting cur rent controller to keep the control loop in an inactive state, and ready for a quick return from the inactive state to the active state, thus providing the desired current signal. As a result, the integrated lighting current controller may be operable to con trol the one or more external light sources using a current signal to provide illumination for acquisition of an image of an object. It is noted that the examples presented above are meant to be illustrative only, and are not intended to limit the function ality or use of the integrated lighting current controller. FIG. liImage Acquisition or Machine Vision System 35 The term “functional unit” may include one or more proces sors and memories and/ or one or more programmable hard ware elements. As used herein, the term “memory medium” BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention can be includes a non-volatile medium, e.g., a magnetic media or 40 obtained when the following detailed description of the pre ferred embodiment is considered in conjunction with the following drawings, in which: FIG. 1 illustrates various embodiments of a general image acquisition system; 45 FIGS. 2 A-C illustrate various embodiments of an image hard disk, optical storage, or ?ash memory; a volatile medium, such as SDRAM memory. Thus, FIG. 1 illustrates an exemplary image acquisition or machine vision system 100, where the smart camera 110 may include a functional unit for performing an image processing function as described below. The smart camera 110 may include one or more function modules 108 which may pro vide various additional functions for the smart camera as will acquisition/processing system for inspecting manufactured be described below. The smart camera 110 may couple to the objects; host computer 102 through a serial bus, a network, or through FIGS. 3A-B are diagrams of a smart camera coupled to a computer system via a network. other means. 50 The host computer 102 may comprise a CPU, a display FIGS. 4A-C are illustration of various components that can connect to a smart camera with an integrated lighting current mouse or keyboard as shown. The computer 102 may operate controller, according to some embodiments of the invention; with the smart camera 110 to analyze, measure or control a FIG. 5A-B illustrate exemplary block diagrams illustrating some embodiments of a smart camera with an integrated 55 device or process 150. Alternatively, the computer 102 may be used only to con?gure a functional unit in the image lighting current controller; acquisition device or one or more of the function modules screen, memory, and one or more input devices such as a 108. In other embodiments, the computer 102 may be omit ted, i.e., the smart camera 110 may operate completely inde FIG. 6 is a block diagram of a smart camera with an integrated lighting current controller, according to one embodiment; and FIGS. 7A-B are block diagrams of an integrated lighting current controller, according to some embodiments. While the invention is susceptible to various modi?cations and alternative forms, speci?c embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the pendent of the computer. 60 The image acquisition system 100 may be used in a manu facturing assembly, test, measurement, automation, and/or control application, among others. For illustration purposes, a 65 unit under test (UUT) 150 is shown which may be positioned by a motion control device 136 (and interface card 138), and imaged and analyzed by the smart camera 110. It is noted that in various other embodiments the UUT 150 may comprise a process or system to be measured and/ or analyzed. US 7,915,570 B2 6 5 back sides. Therefore, the smart camera 110 may include a The smart camera 110 may include a memory medium on housing having a plurality of sides and a lens directly attached to the housing for acquiring an image of an object. In some which computer programs, e. g., text based or graphical pro grams, may be stored. In other embodiments, con?guration information may be stored which may be used to con?gure a programmable hardware element, such as a ?eld program embodiments, the smart camera may also include all the mable gate array (FPGA), comprised in the smart camera (or chassis and/ or the imager/lens. Thus the smart camera may be a function module, or the computer) to perform a measure built into a custom chassis at a later time and may use a ment, control, automation, or analysis function, among oth custom and/ or external imager/lens. As FIG. 3B also shows, the smart camera 110 may include a chassis which includes a plurality of expansion slots for elements shown in FIGS. 5A-B, 6, and 7, but without the ers. The host computer 102 may also include a memory medium on which computer programs may be stored. In one embodiment, another memory medium may be located on a second computer which is coupled to the smart camera 110 or to the host computer 102 through a network, such as a local area network (LAN), a wide area network (WAN), a wireless receiving function modules 108. The function modules 108 may thus provide a mechanism for expanding the capabilities of the smart camera 110 in a modular fashion, such as described in US. Pat. No. 7,327,396. In some embodiments, the chassis does not contain any slots for the function mod ules. FIGS. 4 A-CiConnectivity Options of a Smart Camera network, or the Internet. In this instance, the second computer may operate to provide the program instructions through the FIGS. 4A-C illustrate some embodiments of various con network to the smart camera 110 or host computer 102 for execution. FIGS. 2 A-CiImage Processing Systems nectivity options of a smart camera with an integrated lighting 20 module. It is noted that the smart camera 110 illustrated in FIGS. 2 A-C illustrate image processing or machine vision systems 500 according to various embodiments of the inven FIGS. 4A-C is meant to be exemplary only, and is not tion. The image processing system of FIG. 2A may comprise any particular embodiment. a computer 102 and a smart camera 110, and may further include an actuator (e.g., a motion control device) 192. In one intended to limit the form or function of the smart camera to As indicated in FIG. 4A, in some embodiments, the smart 25 embodiment, the image processing system of FIG. 2B may comprise smart camera 110 and motion control device 192, and may not include computer system 102. The smart camera 110 may include a digital camera that acquires a digital video signal which comprises an image, or 30 a sequence of images, or other data desired to be acquired. In one embodiment, the smart camera 110 may instead include an analog camera that acquires an analog video signal, and the 35 particular application. 40 smart camera 110, according to some embodiments. FIG. 4B shows how an external lighting current controller 622 may be used in conjunction with the smart camera 110. The smart camera may also include one or more ports (not shown) for FIGS. 4B and 4C show various connectivity options for a The smart camera 110 may include a lighting current con troller allowing it to directly connect to one or more lighting sources 606. In some embodiments, only one lighting source is used to illuminate a part being examined. In some embodi ments, multiple lighting sources are used to illuminate a part 612, an external power supply 614, Ethernet expansion I/O 616, operator interface 618 (such as for Human-Machine Interface HMI), and/ or software 620, among others. The abil ity to connect one or more off-the-shelf lighting sources 606 allows the user of the smart camera to directly connect anduse various light sources available on the market as needed for the smart camera 110 may further include A/D converters for converting the analog video signal into a digital image. camera 110 may be able to connect to various devices, such as a lens 280, one or more off-the-shelf lighting sources 606, a camera ?xture 608 for mounting the smart camera 110, an enclosure 610 such as an all-weather enclosure, direct I/O being examined, such as three separate lighting sources that connections with one or more external lighting current con provide Red, Green, and Blue (RGB) illumination. As explained below, the lighting current controller may be oper trollers and/or external power supplies. Also, an external power supply 614 may be used in order to adequately power able to pulse the one or more lighting sources such that the the one or more external lighting sources 606. In some one or more lighting sources are turned on only for duration of embodiments the smart camera may be able to synchronize the actual exposure of one or more images by the smart camera 110. In some embodiments, the lighting current con timing of the integrated universal current controller with tim ing of the external lighting controller. For example, the FPGA and/or the processing unit may ensure that the integrated lighting controller and any external lighting controller are troller may provide a continuous current to the one or more lighting sources instead of a current pulse. In the embodiments of FIGS. 2 A-C, the functional unit in 50 the smart camera 110 (or the computer system 102) may control the actuator 192. Examples of motion control func tions include moving a part or object to be imaged by a able to illuminate one or more UUT’ s using proper timing for a desired exposure interval. FIG. 4C shows how the smart camera 110 with an inte grated lighting current controller 290 may be used to directly camera, rejecting a part on an assembly line, or placing or af?xing components on a part being assembled, or a robotics connect to one or more lighting sources 606, without the need 55 to use either an (additional) external power supply 614 or an application, among others. FIGS. 3 A-BiImage Acquisition System Having a Smart external lighting current controller 622. The solution shown Camera FIGS. 3 A-B illustrate an image acquisition system with a in FIG. 4C thus eliminates external hardware elements to save smart camera 110. The smart camera 110 may include a 60 space, power, and cost that can be incurred by using the external hardware elements. FIG. 5A-BiSmart Camera Block Diagram housing which encloses a portion or all of the smart camera 110 components, or may be comprised on a frame which programmable hardware. As may be seen, this embodiment primarily provides structural support for the smart camera uses a combination of processor/memory 212/214 and pro FIG. 5A is a block diagram of a smart camera 110 with 110 components. In some embodiments, a lens may be attached directly to the housing. In one embodiment, the housing may have a plurality of sides. For example, the plu rality of sides may comprise top, bottom, left, right, front and 65 grammable hardware 206, e.g., FPGA, to perform image processing (and/or other) functions. For example, the pro grammable hardware 206 element in the smart camera 110 may be con?gurable to perform an image processing function US 7,915,570 B2 7 8 on an acquired image. It should be noted that this embodiment is meant to be illustrative only, and is not intended to limit the architecture, components, or form of the smart camera 110. The embodiment of the smart camera 110 illustrated in FIG. 5A may include an imager 282 and a lens 280. The smart camera may also include a functional unit 106, which may comprise a programmable hardware element 206, e.g., a ?eld vision system and the smart camera described in previous ?gures is that the embedded vision system does not necessar ily include a built-in imager 282/lens 280. Instead, the embed ded vision system may couple to an external imager 282/ lens programmable gate array (FPGA), and may also comprise a contain an imager 282, image memory 284, a lens 280, and a processor 212 and memory 214. The programmable hardware element 206, processor 212 and memory 214 may each be coupled to the imager 282 and/or to an image memory 284. images back to the embedded vision system. If the external 280 in order to acquire one or more images. The external camera/lens may be a digital camera or it may be an analog camera. If the external camera is a digital camera, then it may digital bus interface to connect to and send one or more digital The smart camera 110 may also include non-volatile memory camera is an analog camera, then it may contain an analog bus interface to connect to and send analog images back to the 288 coupled to the programmable hardware element 206, the processor 212, the memory 214 and the image memory 284. received analog images. embedded vision system, which would then digitize the The smart camera 110 may also include an T/O connector In some embodiments, the lighting current controller inte 220 which is operable to send and receive signals. The T/O connector 220 may present analog and/ or digital connections grated into the embedded vision system operates in substan tially similar manner to that of a smart camera, including for receiving/providing analog or digital signals. For example providing one or more current signals and/or pulses to one or more external lighting sources as may be needed by the user the T/O connector 220 may enable the smart camera 110 to communicate with computer system 102 (such as the com puter system shown in FIG. 3) to receive a program for 20 performing image processing (and/or other) functions. The FIG. 6 illustrates some embodiments of a smart camera including an integrated lighting current controller. In this smart camera 110 may include a dedicated on-board proces sor 212 and memory 214 in addition to the programmable hardware element 206. As shown, the smart camera 110 may include image and/or an application program. FTG. 6iBlock Diagram of a Smart Camera block diagram various other elements of the smart camera are 25 memory 284 which couples to the programmable hardware 206, the imager 282, the processor 212, memory 214, bus interface 216, the control/data bus 218, and a local bus 217. The image memory 284 may be operable to store a portion of not shown (such as of FIGS. 5A-B) for reasons of simplicity. It should be noted that this embodiment is meant to be illus trative only, and is not intended to limit the architecture, components, or form of the smart camera 110. In some embodiments, the smart camera 110 may include 30 a processing unit 206 such as an FPGA, as well as a lighting current controller 290. The smart camera 110 may also con an image, or one or more images received from the imager 282. The image memory 284 may enable the programmable tain two or more lighting current controllers 290, where each hardware 206 and/or the processor 212 to retrieve the one or controller can connect to, control, and power multiple light more images, operate on them, and return the modi?ed images to the image memory 284. Similarly, one or more of the function modules 108 may be operable to retrieve the sources. The smart camera 110 may also contain a lens (not 35 image from the image memory 284, operate on the image, and return the (possibly) modi?ed image to the image memory 284. As shown, the smart camera 110 may further include bus interface logic 216 and a control/data bus 218. In one embodi ment, the smart camera 110 and/or a function module 108 may comprise a PCT bus-compliant interface card adapted for coupling to the PCT bus of the host computer 102, or adapted for coupling to a PXT (PCT eXtensions for Tnstrumentation) 40 smart camera 110. In some embodiments, the smart camera 45 FIGS. 5A and 5B.) As shown, in one embodiment, the smart camera 110 may 50 ing signals between the smart camera 110 and one or more other devices or cards, such as other smart cameras 110, actuators, smart sensors, and/ or lighting current controllers. In some embodiments, the smart camera 110 may contain choosing a proper lighting source for the machine vision application. In some embodiments the universal lighting cur rent controller may be able to automatically sense the current signal requirements necessary for the connected one or more light sources. In some embodiments a user may need to indi 60 cate to the smart camera the type and/ or requirements of the connected one or more lighting sources. The analog image data created by the imager 282 and/or an below with respect to FIGS. 6-8. FIG. 5B illustrates some embodiments of an embedded vision system with an integrated lighting module that can be used with an external imager 282 and/or lens 280. In some embodiments, an embedded vision system may be used as a smart camera. One of the differences between the embedded In some embodiments the lighting current controller may be a universal lighting current controller, meaning that it can connect to almost any off-the-shelf current controlled light ing source. The combination of the processing unit/FPGA 206 may allow the lighting current controller to adapt the switching power supply to almost any off-the-shelf current controlled lighting source, giving the user great ?exibility in 55 one or more external light sources. The lighting current con troller may be operable to control the one or more external light sources using a current signal (e.g., a current pulse) to provide illumination for acquisition of an image of the UUT. Further discussion of the lighting current controller is shown connect to an external camera and/or lens (such as an analog or digital camera/lens described above with reference to also include local bus interface logic 217. In one embodiment, the local bus interface logic 217 may present a RTST (Real an integrated lighting current controller 290 (referred to herein as a “lighting current controller”) operable to couple to type, duration, and/ or intensity of the current signal provided by the integrated lighting current controller 290 may depend on the type of imager 282 (i.e., imaging element) used by the may not use the imager element 282, and instead it may bus. Time System Integration) bus for routing timing and trigger shown) that may operate in conjunction with an imager ele ment 282 (such as a charge couple device, or CCD) that may be able to generate an analog image and/ or video upon receiv ing light from a lens. Other sensor types are contemplated, such as CMOS, CTS, and/or others. In some embodiments, the 65 external imaging element may be digitized by one or more ADC’s 726. In some embodiments, if an external digital imager is used, then the ADC 726 is not utilized. In some embodiments, the digitized image data can be sent to one or more image buffers 722 (or separate image memory 284 of US 7,915,570 B2 9 10 FIG. 5B). The one or more image buffers 722 may be a part of circuit, this voltage may decay with time, and may cause an incorrect current to be sent through the light source, which in an FPGA/processing unit 206. The data from the image buff turn may cause a bad exposure and/or damage the light source 606. ers may then be used by a separate processor, such as the processor 212 of FIG. SE, to perform an algorithm/image processing/machine vision application. Furthermore, this decay may result in an unwanted delayia period of time when the power supply 718, while In some embodiments, the processing unit 206 may include an exposure generation unit 710 that is operable to generate an exposure generation signal 750. The exposure generation turned on, would need to adjust its output (i.e., the current unit 710 may generate the exposure generation signal 750 in troller’ s 716 ADC may sample the voltage, such as instructed response to an external or internal trigger input 758 (such as a digital input or crossing of an analog threshold), as well as by the FPGA 206 (e.g., using the sample control generation signal 770) because of the lost charge. Thus the microcon signal 754). The PWM output of the microcontroller 716 may be operable to continually refresh the value (i.e., one of the control values of the control loop) until the next time that the from a software generated event. The trigger input 758 may immediately trigger an exposure generation signal 750 or a strobe generation signal 752, or there may be a built-in delay power supply 718 may need to turn on, such as when the next prior to the exposure signal and/or the strobe generation sig strobe generation signal 752 arrives at the active circuit 708 from the processing unit 206. One way to implement this is through a microcontroller with integrated multichannel ADC and PWM DAC. The ADC is used to sample these voltages when turning off the light, for nal 752. A light strobe control generation unit 712 may receive the exposure generation signal 750 and generate a strobe genera tion signal 752. In some embodiments, the light strobe control generation unit 712 may directly receive the trigger signal 758 instead of receiving the exposure generation signal 750. The light strobe control generation unit 712 may generate the 20 strobe generation signal 752 to turn on the one or more light sources 606 for the exposure time of the camera (e.g., the imager 282). Since it is desirable for the light (e.g., from the 25 one or more light sources 606) to be at full brightness before the exposure starts, the strobe generation signal 752 may slightly precede the actual exposure. The strobe generation signal 752 may start activation of an active circuit 708. The active circuit may be operable to which the microcontroller is instructed to do so. The PWM DAC may be used to create a replica of these voltages and feed reactive components, such as loop capacitors, to keep them charged at the desired level. Since this state is kept by using active circuitry, the loop memory can be maintained for an arbitrarily long time interval. FIGS. 7A and 7BiBlock Diagrams of the Lighting current controller FIG. 7A illustrates some embodiments of the integrated lighting current controller, and especially the control loop. It 718 (which may be a part of the active circuit) and supply a should be noted that this embodiment is meant to be illustra tive only, and is not intended to limit the architecture, com ponents, or form of the lighting current controller. control and power pulse (i.e., a current pulse) 770 to the one or more light sources 606. As mentioned above, the lighting above, to properly regulate the switching power supply. How 30 almost instantaneously activate the switching power supply current controller 290 offers the advantage of minimiZing power and current usage, and thus may provide suf?cient The active circuit 708 may use a control loop, as mentioned power to the one or more light sources 606 without using any ever, control loops may take signi?cant time to establish their ?nal control value after starting from their initial state; in other words, when all the reactive components of the system additional external power supplies and with suf?ciently low may be discharged. Adjustments to some of the one or more 35 heat dissipation. control loop compensation network 730 that, in conjunction control variables may occur faster because they represent a smaller percent variation of the output signal. In some cases, it may be necessary to have a memory of the state of the with the power supply 718, is able to almost instantaneously create the current pulse. The control loop compensation net through the complete establishment time. In other words, the In some embodiments, the active circuit 708 may contain a work 730 may be necessary to supply control values to the switching power supply 718. In some embodiments the con 40 control loop so it can be stopped and restarted without going values of the one or more control variables may need to be 45 trol loop compensation network may supply the control val ues directly to the switching power supply 718. The active circuit 708 may receive a pulse width modulated (PWM) signal 756 from a light current setpoint generation unit 720, which may be included in the processing unit/FPGA 206, or it may be a separate element from the processing unit. The PWM signal 756 may be ?ltered and eventually trans mitted to the power supply 718. Since the power supply 718 may be a switching power supply, it may use the PWM signal to control how much current to supply (as a percentage of full acquired and stored for future use. The reactive components of the system may need to be charged to a given energy to remember the last control loop setting, so the control loop can reach the ?nal value in the minimum amount of time possible after an arbitrarily long idle time. 50 Lighting current controllers for a smart camera can be built using switching power supplies, which may be used as an implementation of a control loop. In some embodiments, a switching supply with a single inductor buck-boost topology 55 can be used. In other embodiments, other topologies of switching supplies may be used. In order to adjust the current scale). Thus, the ?ltered PWM signal (see FIGS. 7A-B) may be received by the power supply 718, which then generates pulse 890 to one or more arbitrary values, the current value the current pulse 770 as indicated. The PWM signal may be setting the light current). may be programmed to a speci?c intensity level (usually by Alternatively the power supply can provide continuous generated from the processing unit 206, and thus may be user/ application programmable to a desired output current. 60 settling time issues, this solution has drawbacks. Many light In some embodiments, the compensation sample control generation unit 714 may generate a compensation sample sources may have the ability to be overdriven at a higher signal 754 to indicate to the ADC in the microcontroller 716 when to sample the voltage in the compensation network 73 0. This voltage may be the value that determines where the control loop picks up the next time that the output (i.e., the current signal 770) is turned on. Without the sample and hold power to the light sources. Although this would solve any 65 strobing current level. The strobing current level may be higher than a continuous current level, most likely making strobing current levels incompatible with continuous current levels. The use of a switching power supply (e.g., a current regulator) facilitates overdriving of the one or more lighting US 7,915,570 B2 11 12 sources by allowing direct control of the current output. Thus point for the one or more control values of the control loop is held, and thus the lighting current controller would take con siderably less time to get back to the desired control current overdriving of a light source may occur when the light source is driven with more current than would normally be appro (e.g., the current pulse). priate for a regular continuous operation. Due to the short duration of the current pulse, this overdriving can be done without damage to the light source within a range speci?ed by the light manufacturer. Overdriving the lighting source allows This can be implemented by using a sample and hold circuit 856 that may measure the one or more control values of the control loop (e.g., the inputs to the H(s) transfer func tion unit 850). In some embodiments, the sample and hold the user to obtain more illumination from the same light source than would otherwise be possible. For a lighting current controller with a switching power supply, the current level may be set by a master processor (e.g., the processor 212 and/or the FPGA 206) in the smart camera, such as by using a DAC. As mentioned above, if no measures are taken, stopping the switching power supply 290 for an arbitrarily long time interval may result in the discharge of all the reactive components. In this event the lighting current controller would need to go through the whole estab lishment time in order to reach the ?nal value of the light current. As a solution, a digital sample and hold circuit 856 can be implemented to sample all the control values of inter est, such as loop voltages, and keep a memory of the loop state. As a result, by keeping the memory of the loop state, the key reactive elements in the control loop can be maintained or restored to their operating/active state. In order to integrate both of these devices, smart camera and lighting current controller, into one device, the power density of the lighting current controller may need to be increased. Use of a switching power supply to provide the circuit 856 may store, and/or create a copy, of the measured one or more control values of the control loop. This informa tion may be used to restore or maintain any of the reactive elements inside this RC circuit 730 at working levels (i.e., at active state levels). As a result, since the “working levels” (i.e., from the active state) now became initial conditions, the next time the switching power supply is activated to strobe the one or more light sources, the settling time of the switching power supply should be reduced or even eliminated, substan tially independent of the length of any inactivity interval. 20 25 operable to receive the error signal 870 and generate the 30 as far as response time. Once the switching power supply has been disabled for a long enough time, it may need a settling time which may be orders of magnitude longer than some possible strobing durations for the one or more light sources The lighting controller may be able to turn off the one or more light sources, and ensure that the control current 770 40 Thus, the transfer function unit 850 may be operable to receive the error signal 870 and generate the intermediate settling time of the power supply when it starts after an setpoint signal 884. The switching power supply (e.g., the arbitrarily long inactivity interval. Thus the lighting current 45 current regulator) 860 may be operable to receive the inter mediate setpoint signal and generate the current pulse in response to receiving the intermediate setpoint signal and the user and/or a machine vision application. Once the desired current pulse is established through the power the one or more light sources 606. FIG. 7B illustrates some embodiments of the integrated one or more light sources, the values of the control variables 50 other words, for a ?xed current pulse, the transfer function’s reactive components may be charged to constant values (e.g., the one or more control values). Although the values of the one or more control variables may vary (e.g., depending on the type of the light source), once they settle into a steady state signals may be generated at the same levels and with the same duration as the ?rst user and/or application requested current signal. provided by the control loop may reduce, or eliminate, any inside the switching power supply loop may be stable. In controller to generate a ?rst user and/ or application requested current signal and any subsequent current signals with sub stantially similar timing and current levels. In other words, second and third user and/or application requested current 10’s of microseconds). controller can provide the current signal for any strobing duration and interval that may be needed, such as indicated by error signal 870. In some embodiments, the lighting current controller may need to be initialized the ?rst time the one or more light sources are connected to the system, such that the control loop can settle to the needed levels (which may be unknown until then). The initialization also may allow the lighting current 35 (e. g., milliseconds or 100’s of microseconds compared to (e. g., the current pulse) can get back to the desired value of the output current as fast as possible. This fast response time may be implemented as an error ampli?er 808 of FIG. 7B. The control loop may also use a transfer function unit 850 intermediate setpoint signal 884 in response to receiving the control current (i.e., the current pulse) for the one or more lighting current controllers, while making the power density adequate (in terms of ef?ciency) may have serious limitations The control loop may also use a feedback unit 882 operable to generate a feedback signal 880. A summing unit 852 that may receive the feedback signal 880 and the setpoint PWM signal 869. The summing unit 852 may be further operable to sum the setpoint PWM signal 869 minus the feedback signal 880 to generate an error signal 870. The summing unit 852 55 operation they usually do not change afterwards. lighting current controller in more detail. In some embodi ments, the implementation may be realized using a switching power supply, such as a single inductor buck-boost regulator with programmable current control, and may be based on the Linear Technologies LTC3783 PWM LED Driver and Boost, Flyback and SEPIC Converter, but is not restricted to this speci?c part. In some embodiments, the switching power The active circuit may be able to measure the one or more supply may include various elements such as a power source control values of the control loop for the power supply once it has reached steady state operation, and then maintain them 862, inductor 816, transistor 812, a pass FET transistor 820, an output capacitor 818, and a sensing resistor 824. Other while the light is disconnected (i.e., when the power supply is 60 off). Thus state of the control variables for the transfer func tion 850 may be stored, and the one or more control values of the control loop may be maintained as if the one or more light sources were connected and the control current (e.g., current pulse) was ?owing through them. As a result, any settling time for when the one or more light sources are reconnected may be signi?cantly reduced because the steady state operating implementations of the switching supply are contemplated, and the implementation of this ?gure is shown for exemplary and explanation purposes only. In some embodiments, a control voltage may be set using a PWM generated by an FPGA (or other similar unit) 802 that 65 may be programmed by a user and/or an application program. The PWM signal then may be ?ltered by an FPGA PWM ?lter module 804. After ?ltering, the PWM voltage may very US 7,915,570 B2 13 14 across a de?ned range, which may act as a set point for the or more light sources) may be disconnected to prevent the maintenance strobes from being noticeable to the user. current regulator (see element 860 of FIG. 7A) in order to control the output current (i.e., the current pulse) on the load (i.e., the one or more light sources). This voltage may be mapped to output currents between 0 and full scale. In other embodiments, other ranges of output currents and PWM volt ages are contemplated. Thus the setpoint generator 720 may Thus, a smart camera 110 may utilize a lighting current controller 290 in order to provide a current pulse to one or more light sources. In other words, the smart camera may be able to provide control and power to one or more standard/ off-the-shelf light sources without using external lighting be operable to generate the PWM signal to set the one or more control values of the control loop to a desired level. current controllers and/or additional power supplies. Thus embodiments of the invention use many of the aspects The current regulator 860 (see FIG. 7A) may use a control loop that may include a sense resistor 836 with a high side of an external lighting current controller with the ease of use sense with an embedded error ampli?er 808 and a PWM Embodiments of the invention may also allow the user to connect and power almost any off-the-shelf light source directly to the smart camera. of integrated lighting, yet without sacri?cing quality. modulator 810. As mentioned above, when the lighting con troller starts from a discharged state, it may need time to achieve the desired level of output due to a delay attributed to Although the embodiments above have been described in soft start circuits, output capacitance and/or loop response time, among others. By using the feedback loop, a control considerable detail, numerous variations and modi?cations will become apparent to those skilled in the art once the above voltage may be kept stored in a capacitor even when the light disclosure is fully appreciated. It is intended that the follow ing claims be interpreted to embrace all such variations and source is disconnected. The next time the control loop may be activated, the PWM modulator 810 may start on the last duty 20 cycle and thus bypass any settling time. However, as men What we claim: 1. A smart camera with an integrated universal current tioned above, one or more factors such as capacitor discharge, leakage currents on surrounding elements, any PCB losses, contamination etc., may all contribute to decay in this voltage, and thus over time the memory of the correct duty cycle may be lost. One way to solve this issue is to actively holdthe voltage on a capacitor to compensate for these losses. This can be achieved by a sample and hold circuit 856, which in some embodiments may be created using a microcontroller 832 modi?cations. controller, the smart camera comprising: 25 a processing unit; an imager coupled to the processing unit; and an integrated universal current controller con?gured to couple to one or more external light sources, wherein the integrated universal current controller is further con?g ured to generate a current signal to control operation of 30 the one or more external light sources, wherein the inte grated universal current controller comprises: a switching power supply con?gured to generate the with an integrated ADC (analog-to-digital converter) and PWM DAC (digital-to-analog converter). In some embodi ments, one or more control values of the circuit during the current signal to provide power to the one or more active operation, such as a voltage in the control loop (e.g., across a capacitor in the control loop), may be sampled and external light sources; and an active circuit con?gured to implement a control loop to regulate generation of the current signal, wherein the active circuit is con?gured to sample one 35 stored in memory. A copy of the one or more control values may be created using the microcontroller’s 832 PWM DAC. For example, the measured and then re-generated voltage or more control values of the control loop while the may be looped (such as to the capacitor) via a large resistor. control loop is substantially in an active state, and The control loop may use an RC circuit 730 to facilitate the wherein, in response to a control signal or a user 40 initiated request, the active circuit is con?gured to sample and hold of the control values. In some embodiments, the RC circuit may include capacitors 828A-B, several resis tors 826 and 830A/B, and other elements. restore the one or more control values of the control loop while the control loop is substantially in an The regulator 860 may disconnect the capacitor during the off time of the strobe. This may create high impedance and thus provide a path to the voltage copy on the PWM DAC from the microcontroller 832. Since this is driven by active inactive state. 45 unit to generate the current signal with desired timing and at circuitry (i.e., the microcontroller 832 and the control loop), the voltage on the capacitor may be maintained for as long as needed, without risk of discharge due to any effects such as a desired level. 50 leakage, temperature, contamination on the board, among others. In some embodiments, because the timing of the current pulse should be synchronized to the exposure time of the image sensor to ensure consistent illumination of the object 55 4. The smart camera of claim 1, further comprising: a ?rst port con?gured to couple to an external lighting controller, wherein the smart camera is con?gured to control the external lighting controller, and wherein the smart camera is con?gured to synchronize timing of the integrated universal current controller with timing of the external lighting controller. sure may be sent to the lighting current controller to indicate 60 5. The smart camera of claim 1, wherein the integrated universal current controller further comprises: a setpoint generator con?gured to generate a setpoint ?ciently long that the voltage change on the output capacitor is signi?cant. By brie?y enabling the switching controller, the 3. The smart camera of claim 1, wherein the processing unit is further con?gured to control exposure of the imager and to tune timing of the current signal relative to the exposure of the imager. being imaged, an additional input synchronized to the expo when to strobe. In other embodiments the synchronization may be achieved in other ways, such as by implementing delay elements on the exposure strobe, or by other means. Since the output capacitors can also be discharged, the FPGA 802 may also send maintenance strobes to the lighting current controller as needed, such as when the delay interval is suf 2. The smart camera of claim 1, wherein the integrated universal current controller is con?gurable by the processing pulse width modulation (PWM) signal, wherein the maintenance strobe may restore the voltage on any output setpoint PWM signal is con?gured to set the one or more control values of the control loop to a desired capacitors. During these maintenance strobes, the load (one level; 65